F. A. Perrei — Vesuvius. 



417 



the bottom of which is visible from many parts of the rim. 

 The angle between this floor and the side walls is broken by 

 many talnses corresponding with canals on the walls which 

 give direction to the falling materials. 



By far the best general view of the interior is obtained 

 from the lowest portion of the northerly rim, and by fre- 

 quently visiting this spot with the sun at its greatest north 

 declination — i. e., in June and July — I have been able to com- 



Fig. 5. 



May, 



1906 



August, 

 1909 



Fig. 5. Comparative views of the crater rini as seen from the north. 



pose the photograph reproduced in fig. 1 (Plate I). This 

 shows the entire southern half of the great crater basin with 

 the east, south and west walls, the talus at the bottom and a 

 portion of the crater floor. The average height of the walls 

 is approximately three hundred meters and the diameter across 

 the top from left to right — east to west — about seven hundred 

 and fifty meters. The north to south diameter is somewhat 

 greater and the northwest to southeast a little less. The 

 absence of any standard of comparison renders the picture 

 disappointing to one who is familiar with the noble propor- 

 tions of the crater, but a man on the opposite brink would 



